These are all: electronic, in that they aren't distributed as real, paper books, have no ISBN number, and are generally only available via the author's web site (you won't find them on Amazon.com). They aren't simply on-line, PDF versions of real books.

They're certainly a departure from the traditional model of having a publisher, editor, and real, physical books that could be purchased from book stores. They don't appear to have been through any kind of formal editing or quality control process. The prices seem to differ quite a bit; the first one is $19, the second one is $12, and the last one is $30.77.

For the authors, the appeal is obvious: they get to keep all of the money, and don't have to fool around with a lot of "process".

Consumers, on the other hand, have to consider different aspects: with a "real book", the bureacracy and process exist to guarantee some minimum standards of quality. If you buy an O'Reilly book, you know that it's probably like many of the other books they sell: perhaps it won't stand the test of time like something written by Knuth, but it'll be a pretty good guide to the technology it describes, most likely be someone who is indeed an expert in that area. If I buy some random PDF on the internet, it may come from someone who really knows their stuff, or it may be junk. On the other hand, were this market to grow, theoretically prices could come down. Since the people who are authoring the book don't have to fool around with editing, printing, and so on, and get to keep all the money themselves, they could in theory keep their prices significantly lower than someone creating a more 'traditional' book with a lot of overhead. That is, of course, if the book is one where there is competition in its niche. Right now a lot of these books that pop up on my radar are written by domain experts. However, what's to prevent a lot of people from jumping in and attempting to make a quick buck with a flashy looking web site? Buying books based only on reputation? That might lead to people who are really good authors, but perhaps not well known as "doers" (they didn't invent the technology in question) being left out in the cold. Also, there is something of an unknown quantity about "pdf books". For instance, after raking in a bunch of cash with theirs, 37signals put it on their web site, completely for free. That had to leave the guy who bought it the day before it went free feeling like a bit of a chump. At least with a 'real book', even if the contents are posted on the internet, you have a physical object that belongs to you. I wonder how bad piracy is, and how bad it might be were these to become more popular? Another thing worth noting is that, via services like Lulu.com, it *is* possible to print these out.

In any case, I think things are likely to change with time, as we aren't dealing with a static situation, but rather one where a changing landscape maylead to different outcomes, as the key variables… vary.

I am honestly unsure of what to make of this development. How do you see the market for "home brewed" pdf ebooks evolving?